A carbazole light extraction material and its application

Abstract

The present application provides a compound with a structure as shown in formula (I), whose parent core structure has good planarity and can effectively improve the light extraction efficiency. And the parent core structure can form intramolecular hydrogen bonds, which can convert ultraviolet light into visible light while the structure vibrates. When the compound of the present application is used as a light extraction material, it can have a high refractive index and good ultraviolet light conversion effect. The light extraction material is used in the light extraction layer, and the light extraction layer has a high refractive index, thereby improving the light extraction efficiency and luminous efficiency of the organic electroluminescent device. In addition, the organic electroluminescent device contains the light extraction material of the present application, which can reduce the photoaging effect of ultraviolet light on the organic electroluminescent device through the conversion of ultraviolet light, reduce the damage to the internal materials of the organic electroluminescent device, and further improve the luminous efficiency of the organic electroluminescent device. The display device provided by the present application has a good display effect. #imgabs0#

Description

Technical Field

[0001] The present application relates to the field of organic light-emitting display technology, and in particular to a compound, a light extraction material, an organic electroluminescent device and a display apparatus. Background Art

[0002] An organic electroluminescent device (OLED) is a multilayer organic thin-film structure consisting of a light-emitting layer positioned between a cathode and an anode. When electricity is applied to the light-emitting layer, a waveguide effect, such as total internal reflection, occurs between the layers, reducing the amount of light transmitted. To address this issue, existing technologies often add a light extraction layer above the transparent electrode to improve light extraction efficiency.

[0003] In general, the higher the refractive index of the light extraction layer, the higher the light extraction efficiency from the electrode to the light extraction layer, and the higher the luminous efficiency of the organic electroluminescent device. However, the refractive index of the light extraction material currently used in the light extraction layer is relatively low, and therefore the light extraction efficiency is also relatively low. In addition, in the process of preparing organic electroluminescent devices, when plasma technology is used for flexible packaging, more ultraviolet light will be generated during the plasma glow discharge used, and there is also ultraviolet light in the atmosphere. Existing light extraction materials have strong absorption in the ultraviolet light band (below 400nm) and are prone to photoaging. Since the light extraction material is in the outer layer of the organic electroluminescent device, the light extraction material undergoes photoaging, which can easily cause the internal materials of the organic electroluminescent device to be affected by ultraviolet light, thereby reducing the luminous efficiency of the organic electroluminescent device. Summary of the Invention

[0004] In view of the above problems in the prior art, the object of the present application is to provide a compound, a light extraction material, an organic electroluminescent device and a display device to improve the luminous efficiency of the organic electroluminescent device.

[0005] The first aspect of the present application provides a compound, the structure of which is shown in formula (I):

[0006]

[0007] in,

[0008] R is selected from hydrogen, deuterium, halogen or C1-C6 alkyl; X1 and X2 are each independently selected from hydrogen, unsubstituted or substituted C6-C 50 aryl, unsubstituted or substituted C2-C 50 heteroaryl;

[0009] L1-L3 are each independently selected from a single bond, unsubstituted or Ra-substituted C6-C 50 Arylene, unsubstituted or substituted C2-C 50 Heteroarylene;

[0010] The substituents Ra of each group are independently selected from deuterium, C1-C4 alkyl, C6-C 18 Aryl, C2-C 18 heteroaryl;

[0011] The heteroatoms in the heteroaryl group and the heteroarylene group are each independently selected from O, S, and N.

[0012] The second aspect of the present application provides a light extraction material comprising at least one of the compounds provided in the first aspect of the present application.

[0013] The third aspect of the present application provides an organic electroluminescent device comprising at least one of the light extraction materials provided in the second aspect of the present application.

[0014] A fourth aspect of the present application provides a display device comprising the organic electroluminescent device provided in the third aspect of the present application.

[0015] The compound provided by the present application has a structure as shown in formula (I), and its parent core structure has good planarity, which can effectively improve the light extraction efficiency. And the parent core structure can form intramolecular hydrogen bonds, and the intramolecular hydrogen bonds can convert ultraviolet light into visible light while the structure vibrates. When the compound of the present application is used as a light extraction material, it can have a high refractive index and good ultraviolet light conversion effect. The light extraction material is used in the light extraction layer, and the light extraction layer has a high refractive index, thereby improving the light extraction efficiency and luminous efficiency of the organic electroluminescent device. In addition, the organic electroluminescent device contains the light extraction material of the present application, which can reduce the photoaging effect of ultraviolet light on the organic electroluminescent device through the conversion of ultraviolet light, reduce the damage to the internal materials of the organic electroluminescent device, and further improve the luminous efficiency of the organic electroluminescent device. The display device provided by the present application has a good display effect.

[0016] Of course, it is not necessary to achieve all the advantages described above at the same time when implementing any product or method of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other embodiments can also be obtained based on these drawings.

[0018] Figure 1 Schematic diagram of the structure of a typical organic electroluminescent device;

[0019] Figure 213 are the absorption spectra of Example 13 and Comparative Example 13. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field based on this application are within the scope of protection of this application.

[0021] The first aspect of the present application provides a compound, the structure of which is shown in formula (I):

[0022]

[0023] in,

[0024] R is selected from hydrogen, deuterium, halogen or C1-C6 alkyl;

[0025] X1 and X2 are each independently selected from hydrogen, unsubstituted or Ra-substituted C6-C 50 aryl, unsubstituted or substituted C2-C 50 heteroaryl;

[0026] L1-L3 are each independently selected from a single bond, unsubstituted or Ra-substituted C6-C 50 Arylene, unsubstituted or substituted C2-C 50 Heteroarylene;

[0027] The substituents Ra of each group are independently selected from deuterium, C1-C4 alkyl, C6-C 18 Aryl, C2-C 18 heteroaryl;

[0028] The heteroatoms in the heteroaryl group and the heteroarylene group are each independently selected from O, S, and N.

[0029] The compound provided herein, represented by formula (I), has a core structure with good planarity, effectively improving light extraction efficiency. Furthermore, the core structure can form intramolecular hydrogen bonds, which can convert ultraviolet light into visible light while simultaneously vibrating.

[0030] Specifically, in the compound represented by formula (I), the hydrogen directly attached to the nitrogen atom in carbazole is an easily removable active hydrogen. This active hydrogen, together with the nitrogen atom on the pyridine, can form a hydrogen-bonded six-membered ring as shown in structure (IA). This hydrogen-bonded six-membered ring forms a resonance structure (IB) under ultraviolet light irradiation. This process converts the absorbed higher-energy ultraviolet light into lower-energy visible light.

[0031]

[0032] In addition, in the structure shown in formula (I), R, carbazole, pyridine and L3 are connected to form a linear structure. This structure has low steric hindrance, which is conducive to the close stacking of molecules, thereby increasing the refractive index of the light extraction material, which is conducive to the extraction of effective light emitted by the internal materials of the organic electroluminescent device.

[0033] At the same time, the intermolecular hydrogen bonds behave as attractive forces rather than repulsive forces, making the structure represented by formula (I) more planar, thereby further increasing the packing density between molecules and thereby increasing the light extraction efficiency, which is beneficial for extracting the effective light emitted by the materials inside the organic electroluminescent device.

[0034] Preferably, R is selected from hydrogen, deuterium, halogen or C1-C4 alkyl; X1 and X2 are each independently selected from hydrogen, C6-C4 unsubstituted or substituted by Ra 30 aryl, unsubstituted or substituted C2-C 30 L1-L3 are each independently selected from a single bond, unsubstituted or substituted C6-C 30 Arylene, unsubstituted or substituted C2-C 30 of heteroarylene.

[0035] More preferably, R is selected from hydrogen, deuterium, halogen or C1-C2 alkyl; X1 and X2 are each independently selected from hydrogen, C6-C 18 aryl, unsubstituted or substituted C2-C 18 L1-L3 are each independently selected from a single bond, unsubstituted or substituted C6-C 18 Arylene, unsubstituted or substituted C2-C 18 of heteroarylene.

[0036] More preferably, R is selected from hydrogen, deuterium, halogen or methyl;

[0037] X1 and X2 are each independently selected from hydrogen or any one of the following groups:

[0038]

[0039] L1-L3 are each independently selected from a single bond or any one of the following subunits:

[0040]

[0041] Further preferably, R is selected from hydrogen, deuterium, halogen or methyl;

[0042] X1 and X2 are each independently selected from hydrogen or any one of the following groups:

[0043]

[0044] L1-L3 are each independently selected from a single bond or any one of the following subunits:

[0045]

[0046] In the present application, halogen is preferably F, Cl, Br, or I.

[0047] For example, the compound represented by formula (I) is selected from any one of the following compounds A1-A55:

[0048]

[0049]

[0050] The second aspect of the present application provides a light extraction material, which contains at least one of the compounds provided in the first aspect of the present application. The compound provided in the first aspect of the present application has good planarity, can effectively improve the light extraction efficiency, and can convert ultraviolet light into invisible light. Thus, when the light extraction material of the present application is applied to the light extraction layer, the light extraction layer has a higher refractive index, thereby improving the light extraction efficiency and luminous efficiency of the organic electroluminescent device. Moreover, the organic electroluminescent device contains the light extraction material of the present application, which can reduce the photoaging effect of ultraviolet light on the organic electroluminescent device through the conversion of ultraviolet light, reduce the damage to the internal materials of the organic electroluminescent device, and further improve the luminous efficiency of the organic electroluminescent device.

[0051] In some embodiments of the present application, the refractive index of the light extraction material is ≥1.90. Preferably, the light extraction material has a refractive index of ≥1.90 for red light, ≥1.99 for green light, and ≥2.19 for blue light. This indicates that the light extraction material has a high refractive index under red, green, and blue light. When this light extraction material is applied to a light extraction layer, the light extraction layer has a high refractive index, further improving the light extraction efficiency and luminous efficiency of the organic electroluminescent device.

[0052] In the present application, there is no particular limitation on the type and structure of the organic electroluminescent device. It can be any organic electroluminescent device of various types and structures known in the art, as long as at least one of the light extraction materials provided in the present application can be used.

[0053] The organic electroluminescent device of the present application may be a light-emitting device with a top-emitting structure, which may include an anode, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, a transparent or semi-transparent cathode, and a light extraction layer in sequence on a substrate.

[0054] The organic electroluminescent device of the present application can also be a light-emitting device with a bottom-emitting structure, which can include a light extraction layer, a transparent or semi-transparent anode, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, and a cathode in sequence on a substrate.

[0055] The organic electroluminescent device of the present application can also be a light-emitting device with a double-sided light-emitting structure, which can include a light extraction layer, a transparent or semi-transparent anode, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, a transparent or semi-transparent cathode, and a light extraction layer in sequence on a substrate.

[0056] In addition, there may be an electron blocking layer between the hole transport layer and the light-emitting layer, and there may be a hole blocking layer between the light-emitting layer and the electron transport layer. However, the structure of the organic electroluminescent device of the present application is not limited to the above-mentioned specific structure. If necessary, the above-mentioned layers can be omitted or increased. The present application has no particular restrictions on the thickness of the above-mentioned layers, as long as the purpose of the present application can be achieved. For example, the organic electroluminescent device can sequentially include an anode (100nm to 150nm) made of metal oxide or metal on a substrate, a hole injection layer (5nm to 20nm), a hole transport layer (80nm to 140nm), an electron blocking layer (5nm to 15nm), a light-emitting layer (20nm to 45nm), a hole blocking layer (5nm to 15nm), an electron transport layer (30nm to 40nm), an electron injection layer (0.3nm to 1nm), a transparent or translucent cathode (10nm to 16nm) and a light extraction layer (50nm to 90nm).

[0057] Figure 1 A schematic diagram of a typical organic electroluminescent device is shown, in which, from bottom to top, a substrate 1, a reflective anode 2, a hole injection layer 3, a hole transport layer 4, a light-emitting layer 5, an electron transport layer 6, an electron injection layer 7, a cathode 8, and a light extraction layer 9 are arranged in sequence.

[0058] I understand. Figure 1 The structure of a typical organic electroluminescent device is only schematically shown. The present application is not limited to this structure. The light extraction material of the present application can be used in any type of organic electroluminescent device.

[0059] In the organic electroluminescent device of the present application, except for the light extraction layer comprising the light extraction material provided in the present application, other layers may use various materials used for the layers in the prior art.

[0060] For convenience, the following reference Figure 1The organic electroluminescent device of the present application is described, but this does not mean any limitation on the scope of protection of the present application. It is understood that all organic electroluminescent devices that can use the light extraction material of the present application are within the scope of protection of the present application.

[0061] In the present application, the material of the substrate 1 is not particularly limited, and conventional substrates used in organic electroluminescent devices in the prior art can be used, such as glass, polymer materials, glass and polymer materials with thin film transistor (TFT) components, etc.

[0062] In the present application, the material of the reflective anode 2 is not particularly limited and can be selected from transparent conductive materials such as indium tin oxide (ITO), indium zinc oxide (IZO), tin dioxide (SnO2), zinc oxide (ZnO), low-temperature polycrystalline silicon (LTPS) known in the prior art, or metal materials such as silver and its alloys, aluminum and its alloys, or organic conductive materials such as poly (3,4-ethylenedioxythiophene) (PEDOT), as well as multilayer structures composed of the above materials.

[0063] In the present application, the material of the hole injection layer 3 is not particularly limited, and hole injection materials known in the art can be used, for example, hole transport materials known in the art are selected as hole injection materials.

[0064] In the present application, the hole injection layer 3 may further include a p-type dopant. The type of the p-type dopant is not particularly limited, and various p-type dopants known in the art may be used. For example, the p-type dopant may be selected from at least one of the following p-1 to p-3 compounds:

[0065]

[0066] In the present application, the amount of the p-type dopant is not particularly limited and can be an amount known to those skilled in the art.

[0067] In the present application, the material of the hole transport layer 4 is not particularly limited, and the hole transport layer 4 can be made of hole transport materials known in the art.

[0068] For example, known hole transport materials can be independently selected from but not limited to at least one of the following HT-1 to HT-32 compounds:

[0069]

[0070]

[0071] In the present application, the light-emitting layer 5 may include a blue light-emitting layer, a green light-emitting layer, or a red light-emitting layer. The light-emitting material in the light-emitting layer 5 is not particularly limited, and various light-emitting materials known to those skilled in the art can be used. For example, the light-emitting material may include a host material and a guest material. In the present application, there is no particular limitation on the amount of the host material and the guest material, and the amounts can be any amount known to those skilled in the art.

[0072] In the present application, the host material of the red light emitting layer is not particularly limited, and at least one of the red light emitting layer host materials known in the art can be used. For example, it can be selected from, but not limited to, at least one of the following RH-1 to RH-13 compounds and GPH-1 to GPH-80 compounds:

[0073]

[0074]

[0075]

[0076]

[0077] In the present application, the host material of the green light emitting layer is not particularly limited, and at least one of the green light emitting layer host materials known in the art can be used. For example, it can be selected from but not limited to at least one of the above-mentioned GPH-1 to GPH-80 compounds.

[0078] In the present application, the host material of the blue light emitting layer is not particularly limited, and at least one of the blue light emitting layer host materials known in the art can be used. For example, it can be selected from but not limited to at least one of the following compounds BH-1 to BH-36:

[0079]

[0080]

[0081] In the present application, the guest material of the red light emitting layer is not particularly limited, and at least one of the red light emitting layer guest materials known in the art can be used. For example, it can be selected from, but not limited to, at least one of the following RPD-1 to RPD-28 compounds:

[0082]

[0083] In the present application, the guest material of the green light emitting layer is not particularly limited, and at least one of the green light emitting layer guest materials known in the art can be used. For example, it can be selected from but not limited to at least one of the following GD01 to GD04 compounds:

[0084]

[0085] In the present application, the guest material of the blue light emitting layer is not particularly limited, and at least one of the blue light emitting layer guest materials known in the art can be used. For example, it can be selected from but not limited to at least one of the following BD01 to BD04 compounds:

[0086]

[0087] In the present application, the material of the electron transport layer 6 is not particularly limited, and electron transport materials known in the art can be used. For example, known electron transport materials can be selected from but not limited to at least one of the following compounds ET-1 to ET-61:

[0088]

[0089]

[0090]

[0091]

[0092] In the present application, the electron transport layer 6 may further include an n-type dopant. The type of the n-type dopant is not particularly limited, and various n-type dopants known in the art may be used. For example, the following n-type dopants may be used:

[0093]

[0094] In the present application, the amount of the n-type dopant is not particularly limited and can be an amount known to those skilled in the art.

[0095] In the present application, the material of the electron injection layer 7 is metal Yb.

[0096] In the present application, the material of the cathode 8 is a magnesium-silver mixture (the plating rate ratio of Mg / Ag is 1:9).

[0097] In the present application, the light extraction layer 9 contains at least one of the light extraction materials of the present application, and the light extraction layer 9 may also contain a combination of at least one of the light extraction materials of the present application and known light extraction materials. Currently known light extraction materials are mainly light extraction materials containing aromatic amine compounds. In order to improve the light extraction rate, the light extraction layer 9 of the present application is arranged on a transparent electrode (cathode and / or reflective anode) on the light-emitting side. It is required that the refractive index of the light extraction layer is greater than the refractive index of the electrode and that it can transmit visible light. The light extraction layer 9 of the present application contains the light extraction material of the present application, has a higher refractive index, and can therefore provide a high light extraction rate.

[0098] In some embodiments of the present application, the thickness of the light extraction layer 9 is 50 nm to 90 nm, preferably 60 nm to 80 nm.

[0099] Optionally, the organic electroluminescent device may include an electron blocking layer. In the present application, the material of the electron blocking layer is not particularly limited, and electron blocking layer materials known in the art can be used. For example, it can be selected from, but not limited to, the following EB-1 to EB-5 compounds:

[0100]

[0101] Optionally, the organic electroluminescent device may include a hole blocking layer. In the present application, the material of the hole blocking layer is not particularly limited, and hole blocking layer materials known in the art may be used. For example, it may be selected from, but not limited to, at least one of the above-mentioned compounds ET-1 to ET-61.

[0102] A fourth aspect of the present application provides a display device comprising the organic electroluminescent device provided herein, which has excellent display effects. The display device includes but is not limited to a monitor, a television, a mobile communication terminal, a tablet computer, and the like.

[0103] The present application does not particularly limit the preparation method of the organic electroluminescent device, and any method known in the art may be used. For example, the preparation method of the organic electroluminescent device may include but is not limited to the following steps:

[0104] (1) Cleaning the reflective anode 2 on the substrate 1 of the top-emitting organic electroluminescent device by using a cleaning machine through steps such as chemical cleaning, water cleaning, brush cleaning, high-pressure water cleaning, and air knife cleaning, and then heating treatment;

[0105] (2) vacuum evaporating a hole injection layer 3 on the reflective anode 2, wherein the hole injection layer 3 contains a hole injection material and a p-type dopant;

[0106] (3) vacuum evaporating a hole transport material on the hole injection layer 3 to form the hole transport layer 4;

[0107] (4) vacuum evaporating a light-emitting layer 5 on the hole transport layer 4, wherein the light-emitting layer 5 contains a host material and a guest material;

[0108] (5) vacuum evaporating an electron transport material on the light-emitting layer 5 to form an electron transport layer 6, wherein the electron transport layer 6 comprises an electron transport material and an n-type dopant;

[0109] (6) vacuum evaporating an electron injection material on the electron transport layer 6 to form the electron injection layer 7;

[0110] (7) vacuum evaporating a cathode material on the electron injection layer 7 to form the cathode 8;

[0111] (8) Finally, a light extraction material is evaporated on the cathode 8 to form a light extraction layer 9 .

[0112] The above only describes a typical structure of an organic electroluminescent device and its preparation method. It should be understood that the present application is not limited to this structure.

[0113] Synthesis Example 1: Synthesis of Compound A2

[0114]

[0115] To a reaction flask, 100 mmol of p-chloroaniline, 200 mmol of 3-bromodibenzothiophene, 200 mmol of sodium tert-butoxide, 1 mol% of tris(dibenzylidene-base acetone)dipalladium (Pd2(dba)3), and 2 mol% of 2-dicyclohexylphosphino-2,4,6-triisopropylbiphenyl (XPhos) were added and refluxed. After completion, the reaction was stopped and the mixture was cooled to room temperature. Water was added, and the organic phase was concentrated to obtain a white solid. The solid was filtered and washed with water. The resulting solid was recrystallized from toluene to obtain a white powder M1. The amount of Pd2(dba)3 added was 1 mol% of the p-chloroaniline, and the amount of XPhos added was 2 mol% of the p-chloroaniline.

[0116] 100 mmol of M1, 120 mmol of pinacol diboronate, 19.6 g of potassium acetate (200 mmol), and 2.3 L of toluene were added to a reaction flask. 0.6 mol% of Pd2(dba)3 and 2.4 mol% of XPhos were also added, and the reaction was continued at 105°C for 12 hours. After the reaction was completed, the reaction was stopped and the reactants were cooled to room temperature. Water was added, and the organic phase was concentrated to obtain a white solid. The solid was filtered and washed with water. The obtained solid was recrystallized and purified from toluene to obtain a white powder M2. The amount of Pd2(dba)3 added was 0.6 mol% of M1, and the amount of XPhos added was 2.4 mol% of M1.

[0117] To a reaction flask, add 100 mmol of 2-bromo-4-chlorotoluene, 120 mmol of n-butyllithium, 130 mmol of tributyl borate, and 1.2 L of tetrahydrofuran (THF) and react at -90°C to -80°C for 12 hours. After completion, the reaction was stopped and the mixture was returned to room temperature. Water was added, filtered, and washed with water. The resulting solid was purified by recrystallization from toluene to obtain a white powder M3.

[0118] To a reaction flask, 100 mmol of M3, 100 mmol of 2-bromoaniline, 27.6 g of potassium carbonate (200 mmol), 2.1 L of toluene, 700 ml of ethanol, and 700 ml of water were added. 0.6 mol% of tetrakis(triphenylphosphine)palladium (Pd(PPh3)4) was then added and the mixture was reacted at 95°C for 12 hours. After completion of the reaction, the reaction was stopped and the reactants were cooled to room temperature, water was added, filtered, and washed with water. The resulting solid was recrystallized and purified from toluene to obtain a white powder, M4. The amount of Pd(PPh3)4 added was 1 mol% of the 2-bromoaniline.

[0119] To a reaction flask, 100 mmol of M4, 120 mmol of pinacol diboronate, 19.6 g of potassium acetate (200 mmol), and 2.3 L of toluene were added. 0.6 mol% of Pd2(dba)3 and 2.4 mol% of XPhos were also added, and the reaction was continued at 105°C for 12 hours. After completion of the reaction, the reaction was stopped and the reactants were cooled to room temperature. Water was added, and the organic phase was concentrated to obtain a white solid. The solid was filtered and washed with water. The obtained solid was recrystallized and purified from toluene to obtain a white powder M5. The amount of Pd2(dba)3 added was 0.6 mol% of M4, and the amount of XPhos added was 2.4 mol% of M4.

[0120] To a reaction flask were added 100 mmol of M5, 100 mmol of 2-bromo-5-chloropyridine, 41.4 g of potassium carbonate (300 mmol), 800 ml of THF, and 200 ml of water. 1 mol% of Pd(PPh3)4 was then added, and the reaction was continued at 60°C for 12 h. After completion of the reaction, the reaction was stopped, and the reactants were cooled to room temperature. Water was added, and the organic phase was concentrated to obtain a white solid, which was filtered and washed with water. The resulting solid was recrystallized and purified from toluene to obtain a white powder, M6. The amount of Pd(PPh3)4 added was 1 mol% of the 2-bromo-5-chloropyridine.

[0121] 800 ml of o-dichlorobenzene, 340 mmol of triphenylphosphine, and 100 mmol of M6 were added to a reaction flask and reacted at 180°C for 12 h. After completion, the reaction was stopped and cooled to room temperature. Water was added, and the organic phase was concentrated to obtain a white solid. This was filtered and washed with water. The resulting solid was recrystallized from toluene to obtain a white powder, M7. The amount of Pd(PPh3)4 added was 1 mol% of M6.

[0122] To a reaction flask, 100 mmol of M2, 100 mmol of M7, 41.4 g of potassium carbonate (300 mmol), 800 ml of THF, and 200 ml of water were added, along with 1 mol% of Pd(PPh3)4. The mixture was reacted at 120°C for 12 h. After completion, the reaction was stopped and the reactants were cooled to room temperature. Water was added, and the organic phase was concentrated to obtain a white solid. The solid was filtered and washed with water, and then recrystallized from toluene to obtain Compound A2, a white powder. The amount of Pd(PPh3)4 added was 1 mol% of M2.

[0123] 1 H NMR (400MHz, Chloroform-d) δ8.97(d,J=8.4Hz,1H),8.27(d,J=7.6,6.4Hz,2H),8.03(d,J=7.6Hz,1H),7.94(d,J=7.2Hz,1H),7.87(d,J=7.6Hz,3H),7.77( d,J=7.6Hz,1H),7.68(d,J=7.2Hz,2H),7.65–7.58(m,4H),7.53–7.46(m,3H), 7.35–7.25(m,6H),7.22(t,J=7.2Hz,1H),7.14(d,J=7.6Hz,2H),2.55(s,3H).

[0124] Synthesis Example 2: Synthesis of Compound A3

[0125]

[0126] To a reaction flask were added 100 mmol of 3-bromodibenzofuran, 100 mmol of 4-aminophenylboronic acid, 27.6 g of potassium carbonate (200 mmol), 2.1 L of toluene, 700 ml of ethanol, and 700 ml of water. 0.6 mol% of Pd(PPh3)4 was then added and the mixture was reacted at 95°C for 12 hours. After completion of the reaction, the reaction was stopped and the product was cooled to room temperature, water was added, filtered, and washed with water. The resulting solid was recrystallized and purified from toluene to obtain a white powder, M1. The amount of Pd(PPh3)4 added was 1 mol% of the 4-aminophenylboronic acid.

[0127] To a reaction flask, 100 mmol of M1, 100 mmol of 3-chlorodibenzothiophene, 28.83 g of sodium tert-butoxide (300 mmol), and 800 ml of xylene were added. 1 mol% of Pd(dba) was then added and the mixture was allowed to react at 120°C for 12 hours. After completion, the reaction was stopped and the mixture was cooled to room temperature, water was added, filtered, and washed. The resulting solid was recrystallized from toluene to obtain M3 as a white powder. The amount of Pd(dba) added was 1 mol% of the 3-chlorodibenzothiophene.

[0128] To a reaction flask, 100 mmol of M2, 100 mmol of M3, 28.83 g of sodium tert-butoxide (300 mmol), and 800 ml of xylene were added, along with 1 mol% of Pd(dba). The mixture was reacted at 120°C for 12 h. After completion, the reaction was stopped and the product was cooled to room temperature, water was added, filtered, and washed. The resulting solid was purified by recrystallization from toluene to obtain Compound A3, a white powder. The amount of Pd(dba) added was 1 mol% of M1.

[0129] 1 H NMR (400MHz, Chloroform-d) δ8.39(d,J=8.4Hz,1H),8.28(d,J=7.6Hz,1H),8.02(d,J=8.0Hz,2H),7.88(d,J=7.6Hz,1H),7.77(d,J=12.0Hz,2H),7.71–7. 62(m,2H),7.57(d,J=7.2Hz,2H),7.55–7.49(m,6H),7.46(d,J=7.6Hz,2H),7 .40(d,J=12.4Hz,2H),7.32–7.22(m,7H),7.15(d,J=7.6Hz,1H),2.57(s,3H).

[0130] Synthesis Example 3: Synthesis of Compound A8

[0131]

[0132] Add 100 mmol of m-chlorobromobenzene, 120 mmol of n-butyllithium, 130 mmol of tributyl borate, and 1.2 L of THF to a reaction flask and react at -90°C to -80°C for 12 hours. After completion, stop the reaction, return the reactants to room temperature, add water, filter, and wash. The resulting solid is purified by recrystallization from toluene to obtain a white powder, M1.

[0133] To a reaction flask were added 100 mmol of M1, 100 mmol of 1-bromo-2-nitrobenzene, 27.6 g of potassium carbonate (200 mmol), 2.1 L of toluene, 700 ml of ethanol, and 700 ml of water. 0.6 mol% of Pd(PPh3)4 was then added and the mixture was reacted at 95°C for 12 hours. After completion of the reaction, the reaction was stopped and the product was cooled to room temperature, water was added, filtered, and washed with water. The resulting solid was recrystallized and purified from toluene to obtain a white powder, M2. The amount of Pd(PPh3)4 added was 1 mol% of the 2-bromoaniline.

[0134] 100 mmol of M2, 120 mmol of pinacol diboronate, 19.6 g of potassium acetate (200 mmol), and 2.3 L of toluene were added to a reaction flask. 0.6 mol% of Pd2(dba)3 and 2.4 mol% of XPhos were also added, and the reaction was continued at 105°C for 12 hours. After the reaction was completed, the reaction was stopped and the reactants were cooled to room temperature. Water was added, and the organic phase was concentrated to obtain a white solid. The solid was filtered and washed with water. The obtained solid was recrystallized and purified from toluene to obtain a white powder M3. The amount of Pd2(dba)3 added was 0.6 mol% of M2, and the amount of XPhos added was 2.4 mol% of M2.

[0135] 100 mmol of M3, 100 mmol of 2-bromo-5-chloropyridine, 41.4 g of potassium carbonate (300 mmol), 800 ml of THF, and 200 ml of water were added to a reaction flask, and 1 mol% of Pd(PPh3)4 was added. The reaction was allowed to proceed at 60°C for 12 hours. After completion of the reaction, the reaction was stopped, and the reactants were cooled to room temperature. Water was added, and the organic phase was concentrated to obtain a white solid, which was filtered and washed with water. The obtained solid was recrystallized and purified from toluene to obtain a white powder M4. The amount of Pd(PPh3)4 added was 1 mol% of the 2-bromo-5-chloropyridine.

[0136] 800 ml of o-dichlorobenzene, 340 mmol of triphenylphosphine, and 100 mmol of M4 were added to a reaction flask and reacted at 180°C for 12 hours. After completion, the reaction was stopped and cooled to room temperature. Water was added, and the organic phase was concentrated to obtain a white solid. This was filtered and washed with water. The resulting solid was recrystallized from toluene to obtain a white powder, M5. The amount of Pd(PPh3)4 added was 1 mol% of M4.

[0137] To a reaction flask, 100 mmol of 2-bromobenzo[9,10]phenanthrene, 100 mmol of 4-aminophenylboronic acid, 27.6 g of potassium carbonate (200 mmol), 2.1 L of toluene, 700 ml of ethanol, and 700 ml of water were added. 0.6 mol% of Pd(PPh3)4 was then added and the mixture was allowed to react at 95°C for 12 hours. After completion, the reaction was stopped and the mixture was cooled to room temperature, water was added, filtered, and washed. The resulting solid was recrystallized from toluene to obtain a white powder, M6. The amount of Pd(PPh3)4 added was 1 mol% of the 4-aminophenylboronic acid.

[0138] To a reaction flask, 100 mmol of M6, 100 mmol of 3-chlorodibenzothiophene, 28.83 g of sodium tert-butoxide (300 mmol), and 800 ml of xylene were added. 1 mol% of Pd(dba) was then added and the mixture was allowed to react at 120°C for 12 hours. After completion, the reaction was stopped and the mixture was cooled to room temperature, water was added, filtered, and washed. The resulting solid was recrystallized from toluene to obtain M7 as a white powder. The amount of Pd(dba) added was 1 mol% of the 3-chlorodibenzothiophene.

[0139] To a reaction flask, 100 mmol of M5, 100 mmol of M7, 28.83 g of sodium tert-butoxide (300 mmol), and 800 ml of xylene were added. 1 mol% of Pd(dba) was also added, and the reaction was incubated at 120°C for 12 h. After completion, the reaction was stopped, and the product was cooled to room temperature, added with water, filtered, and washed. The resulting solid was purified by recrystallization from toluene to obtain Compound A8 as a white powder. The amount of Pd(dba) added was 1 mol% of M5.

[0140] 1 H NMR(400MHz,Chloroform-d)δ9.50(d,J=8.0Hz,1H),8.67(d,J=7.6Hz,1H),8.28(t,J=7.6Hz,2H),8.16(d,J=7.2Hz,1H),8.11(d,J=7 .6Hz,1H),8.03(d,J=7.6Hz,1H),7.89–7.81(m,3H),7.71–7.65(m,3H),7.52–7.37(m,13H),7.31(d,J=7.6Hz,2H),7.23–7.16(m,4H).

[0141] Synthesis Example 4: Synthesis of Compound A14

[0142]

[0143] To a reaction flask were added 100 mmol of 2-bromonaphthalene, 100 mmol of 4-aminophenylboronic acid, 27.6 g of potassium carbonate (200 mmol), 2.1 L of toluene, 700 ml of ethanol, and 700 ml of water. 0.6 mol% of Pd(PPh3)4 was then added and the mixture was reacted at 95°C for 12 hours. After completion of the reaction, the reaction was stopped and the product was cooled to room temperature, water was added, filtered, and washed with water. The resulting solid was recrystallized and purified from toluene to obtain a white powder, M1. The amount of Pd(PPh3)4 added was 1 mol% of the 2-bromonaphthalene.

[0144] 100 mmol of 3-bromodibenzofuran, 100 mmol of 4-chlorophenylboronic acid, 27.6 g of potassium carbonate (200 mmol), 2.1 L of toluene, 700 ml of ethanol, and 700 ml of water were added to a reaction flask. 0.6 mol% of Pd(PPh3)4 was then added and the mixture was reacted at 95°C for 12 hours. After the reaction was completed, the reaction was stopped and the reactants were cooled to room temperature, water was added, filtered, and washed with water. The resulting solid was recrystallized and purified from toluene to obtain a white powder M2. The amount of Pd(PPh3)4 added was 1 mol% of the 3-bromodibenzofuran.

[0145] To a reaction flask, 100 mmol of M1, 100 mmol of M2, 28.83 g of sodium tert-butoxide (300 mmol), and 800 ml of xylene were added. 1 mol% of Pd(dba) was then added and the mixture was allowed to react at 120°C for 12 hours. After completion, the reaction was stopped and the mixture was cooled to room temperature, water was added, filtered, and washed. The resulting solid was recrystallized from toluene to obtain a white powder, M3. The amount of Pd(dba) added was 1 mol% of M1.

[0146] To a reaction flask, 100 mmol of M3, 100 mmol of M4, 28.83 g of sodium tert-butoxide (300 mmol), and 800 ml of xylene were added. 1 mol% of Pd(dba) was also added, and the reaction was incubated at 120°C for 12 h. After completion, the reaction was stopped and the mixture was cooled to room temperature, water was added, filtered, and washed. The resulting solid was purified by recrystallization from toluene to obtain compound 14 as a white powder. The amount of Pd(dba) added was 1 mol% of M3.

[0147] 1H NMR(400MHz,Chloroform-d)δ8.68(d,J=7.6Hz,1H),8.06–7.92(m,4H),7.91–7.85(m,1H),7.76(d,J=9.6Hz,2H),7 .69–7.64(m,2H),7.58–7.43(m,13H),7.41(d,J=7.6Hz,1H),7.38(t,J=7.2Hz,1H),7.33–7.20(m,7H),2.55(s,3H).

[0148] Synthesis Example 5: Synthesis of Compound A34

[0149]

[0150] To a reaction flask were added 100 mmol of 4-bromophenylboronic acid, 100 mmol of 2-bromobenzoxazole, 27.6 g of potassium carbonate (200 mmol), 2.1 L of toluene, 700 ml of ethanol, and 700 ml of water. 0.6 mol% of Pd(PPh3)4 was then added and the mixture was reacted at 95°C for 12 hours. After completion of the reaction, the reaction was stopped and the reactants were cooled to room temperature, water was added, filtered, and washed with water. The resulting solid was recrystallized and purified from toluene to obtain a white powder, M1. The amount of Pd(PPh3)4 added was 1 mol% of the 4-bromophenylboronic acid.

[0151] To a reaction flask, 100 mmol of p-chloroaniline, 200 mmol of M1, 200 mmol of sodium tert-butoxide, 1 mol% of Pd2(dba)3, and 2 mol% of XPhos were added and refluxed. After completion, the reaction was stopped and the mixture was cooled to room temperature. Water was added, and the organic phase was concentrated to obtain a white solid. The solid was filtered and washed with water. The resulting solid was recrystallized from toluene to obtain a white powder, M2. The amount of Pd2(dba)3 added was 1 mol% of the p-chloroaniline, and the amount of XPhos added was 2 mol% of the p-chloroaniline.

[0152] 100 mmol of M2, 120 mmol of pinacol diboronate, 19.6 g of potassium acetate (200 mmol), and 2.3 L of toluene were added to a reaction flask. 0.6 mol% of Pd2(dba)3 and 2.4 mol% of XPhos were also added, and the reaction was continued at 105°C for 12 hours. After the reaction was completed, the reaction was stopped and the reactants were cooled to room temperature. Water was added, and the organic phase was concentrated to obtain a white solid. The solid was filtered and washed with water. The obtained solid was recrystallized and purified from toluene to obtain a white powder M3. The amount of Pd2(dba)3 added was 0.6 mol% of M2, and the amount of XPhos added was 2.4 mol% of M2.

[0153] To a reaction flask, 100 mmol of M3, 100 mmol of M4, 41.4 g of potassium carbonate (300 mmol), 800 ml of THF, and 200 ml of water were added. 1 mol% of Pd(PPh3)4 was also added, and the reaction was incubated at 60°C for 12 h. After completion, the reaction was stopped and the mixture was cooled to room temperature. Water was added, and the organic phase was concentrated to obtain a white solid. The solid was filtered and washed with water, and then recrystallized from toluene to obtain compound A34 as a white powder. The amount of Pd(PPh3)4 added was 1 mol% of M3.

[0154] 1 H NMR(400MHz,Chloroform-d)δ8.97(d,J=8.4Hz,1H),8.03(d,J=7.6Hz,1H),7.95(d,J=7.2Hz,1H),7.91–7 .83(m,5H),7.77(d,J=7.6Hz,1H),7.65–7.59(m,4H),7.51–7.41(m,7H),7.30–7.24(m,9H),2.55(s,3H).s

[0155] Synthesis Example 6: Synthesis of Compound A28

[0156]

[0157] To a reaction flask, 100 mmol of 2-bromobenzo[9,10]phenanthrene, 100 mmol of 4-aminophenylboronic acid, 27.6 g of potassium carbonate (200 mmol), 2.1 L of toluene, 700 ml of ethanol, and 700 ml of water were added. 0.6 mol% of Pd(PPh3)4 was then added and the mixture was allowed to react at 95°C for 12 hours. After completion, the reaction was stopped and the product was cooled to room temperature, water was added, filtered, and washed. The resulting solid was recrystallized from toluene to obtain a white powder, M1. The amount of Pd(PPh3)4 added was 0.6 mol% of the 4-aminophenylboronic acid.

[0158] To a reaction flask were added 100 mmol of 2-bromonaphthalene, 100 mmol of 4-chlorophenylboronic acid, 27.6 g of potassium carbonate (200 mmol), 2.1 L of toluene, 700 ml of ethanol, and 700 ml of water. 0.6 mol% of Pd(PPh3)4 was then added and the mixture was reacted at 95°C for 12 hours. After completion of the reaction, the reaction was stopped and the product was cooled to room temperature, water was added, filtered, and washed with water. The resulting solid was recrystallized and purified from toluene to obtain a white powder, M2. The amount of Pd(PPh3)4 added was 0.6 mol% based on the 2-bromonaphthalene.

[0159] To a reaction flask, 100 mmol of M1, 100 mmol of M2, 28.83 g of sodium tert-butoxide (300 mmol), and 800 ml of xylene were added. 1 mol% of Pd(dba) was then added and the mixture was allowed to react at 120°C for 12 hours. After completion, the reaction was stopped and the mixture was cooled to room temperature, water was added, filtered, and washed. The resulting solid was recrystallized from toluene to obtain a white powder, M3. The amount of Pd(dba) added was 1 mol% of M1.

[0160] To a reaction flask, 100 mmol of M3, 100 mmol of M4, 28.83 g of sodium tert-butoxide (300 mmol), and 800 ml of xylene were added, along with 1 mol% of Pd(dba). The mixture was reacted at 120°C for 12 h. After completion, the reaction was stopped and the product was cooled to room temperature, water was added, filtered, and washed. The resulting solid was purified by recrystallization from toluene to obtain Compound A28, a white powder. The amount of Pd(dba) added was 1 mol% of M3.

[0161] 1H NMR(400MHz,Chloroform-d)δ9.50(d,J=7.6Hz,1H),8.68(d,J=8.4Hz,1H),8.33–8 .26(m,2H),8.17(d,J=7.42Hz,1H),8.11(d,J=7.2Hz,1H),8.03(d,J=7..6Hz,1H),8 .01–7.92(m,2H),7.88(d,J=7.6Hz,1H),7.82(d,J=10.4Hz,2H),7.68(d,J=6.8Hz, 3H),7.60–7.48(m,10H),7.45–7.37(m,6H),7.29(d,J=7.6,1H),7.23–7.16(m,5H).

[0162] Other compounds of the present application can be synthesized by selecting appropriate raw materials according to the ideas of Synthesis Examples 1-6, or by selecting any other appropriate method and raw materials.

[0163] Example 1

[0164] Glass substrates coated with an ITO transparent conductive layer were ultrasonically treated in a commercial cleaning agent, rinsed in deionized water, ultrasonically degreased in an acetone-ethanol mixed solvent, baked in a clean environment to completely remove water, cleaned with ultraviolet light and ozone, and bombarded with a low-energy cation beam.

[0165] Then, the glass substrate with the 150nm thick reflective anode was placed in a vacuum chamber and evacuated to a vacuum of less than 10 -5A hole injection layer is vacuum-deposited on the reflective anode layer. The hole injection layer comprises a hole transport material HT-21 and a p-type dopant p-3 at a mass ratio of 3%. The deposition rate is 0.1 nm / s and the deposition film thickness is 10 nm.

[0166] Then, a hole transport material HT-32 was vacuum evaporated on the hole injection layer as a hole transport layer, wherein the evaporation rate was 0.1 nm / s and the evaporation film thickness was 130 nm;

[0167] Then, a light-emitting layer was vacuum-evaporated on the hole transport layer. The light-emitting layer included a host material GHP-16 and a guest material RPD-1. The evaporation was performed using a multi-source co-evaporation method. The evaporation rate of the host material GHP-16 was adjusted to 0.1 nm / s, and the evaporation rate of the guest material RPD-1 was adjusted to 3% of the evaporation rate of the host material GHP-16. The total film thickness was 30 nm.

[0168] Then, an electron transport layer with a thickness of 35 nm was vacuum-deposited on the light-emitting layer. The electron transport layer contained an electron transport material ET-61 and an n-type dopant n-1, wherein the content of the n-type dopant was 50 mol %.

[0169] Then, Yb with a thickness of 1 nm was vacuum evaporated on the electron transport layer as an electron injection layer at a deposition rate of 0.1 nm / s;

[0170] Then, a magnesium-silver mixture (Mg / Ag plating ratio of 1:9) with a thickness of 15 nm was evaporated on the electron injection layer as a cathode at a deposition rate of 0.1 nm / s.

[0171] Finally, a light extraction layer with a thickness of 50 nm was vacuum evaporated on the cathode at a deposition rate of 0.1 nm / s. The material of the light extraction layer was compound A2.

[0172] The organic electroluminescent device of this embodiment emits red light.

[0173] Examples 2-5

[0174] Except for adjusting the thickness of the light extraction layer according to Table 1, the rest is the same as Example 1.

[0175] Example 6

[0176] The reaction was the same as in Example 1 except that compound GPH-44 was used instead of GHP-16 and compound GD04 was used instead of RPD-1.

[0177] The organic electroluminescent device of this embodiment emits green light.

[0178] Examples 7-10

[0179] Except for adjusting the thickness of the light extraction layer according to Table 1, the rest is the same as Example 6.

[0180] Example 11

[0181] The reaction was the same as in Example 1 except that compound BH-1 was used instead of GHP-16 and compound BD01 was used instead of RPD-1.

[0182] The organic electroluminescent device of this embodiment emits blue light.

[0183] Examples 12-15

[0184] Except for adjusting the thickness of the light extraction layer according to Table 1, the rest is the same as Example 11.

[0185] Examples 16, 19, 22, 25, and 28

[0186] Except that compound A2 was replaced by compound A3, A8, A14, A34 and A28 respectively, the rest was the same as Example 3.

[0187] Examples 17, 20, 23, 26, and 29

[0188] The process was the same as in Example 8 except that Compound A3, A8, A14, A34 and A28 were used instead of Compound A2.

[0189] Examples 18, 21, 24, 27, and 30

[0190] Except that Compound A2 was replaced by Compound A3, A8, A14, A34, and A28, respectively, the rest was the same as Example 13.

[0191] Comparative Example 1

[0192] The reaction was the same as in Example 1 except that Compound 1-1 shown below was used instead of Compound A2.

[0193] Comparative Examples 2-5

[0194] Except for adjusting the thickness of the light extraction layer according to Table 1, the rest is the same as Comparative Example 1.

[0195] Comparative Example 6

[0196] Except that compound 1-1 was used instead of compound A2, the rest was the same as Example 6.

[0197] Comparative Examples 7-10

[0198] Except for adjusting the thickness of the light extraction layer according to Table 1, the rest is the same as Comparative Example 6.

[0199] Comparative Example 11

[0200] Except that compound 1-1 was used instead of compound A2, the rest was the same as Example 11.

[0201] Comparative Examples 12-15

[0202] Except for adjusting the thickness of the light extraction layer according to Table 1, the rest is the same as Comparative Example 11.

[0203] Comparative Example 16

[0204] The reaction was the same as in Comparative Example 3 except that Compound 1-2 shown below was used instead of Compound 1-1.

[0205] Comparative Example 17

[0206] Except that compound 1-2 was used instead of compound 1-1, the rest was the same as Comparative Example 8.

[0207] Comparative Example 18

[0208] Except that compound 1-2 was used instead of compound 1-1, the rest was the same as Comparative Example 13.

[0209]

[0210] Performance testing of organic electroluminescent devices:

[0211] Specifically, the BJV test system is used to test the current efficiency and CIE color coordinates of organic electroluminescent devices.

[0212] For blue light devices, the blue light index (BI) is used to examine their luminous efficiency, and the CIEy value is mainly used to evaluate the saturation of the blue light color. The blue light index is obtained by dividing the current efficiency of the blue light device by the CIEy value. A larger CIEy value indicates that the blue light color has redshifted, and a smaller CIEy value indicates that the blue light color has blueshifted. Current efficiency is used to evaluate the luminous efficiency of green and red light devices. The color changes of green and red light devices are mainly evaluated by the CIEx value. A larger CIEx indicates a redshift of luminescence, and a smaller CIEx indicates a blueshift of luminescence.

[0213] Refractive index test:

[0214] The measurement instrument was a Radiation Technology Version-1.0.1.4 spectroscopic ellipsometer; the glass substrate was 200 mm x 200 mm, and the light extraction material film was 80 nm thick. The refractive index (n) of the compound was measured at different wavelengths.

[0215] UV aging test:

[0216] First, the voltage and BI value of the blue organic electroluminescent device are tested and recorded as the initial voltage and initial BI.

[0217] The prepared blue organic electroluminescent device was placed in a QUV-spray UV aging box, using a lamp with a wavelength of 340nm and a brightness of 0.8W / m 2 ; The temperature is room temperature; after 16 hours of ultraviolet light irradiation, take it out and place it in a black box to avoid light. The irradiation and light-avoidance process is repeated 5 times, and then the voltage and BI value of the blue light organic electroluminescent device are tested, which are recorded as light aging voltage and light aging BI.

[0218] Light aging voltage change = light aging voltage / initial voltage × 100%;

[0219] Photoaging BI change = photoaging BI / initial BI×100%.

[0220] Comparative experiment on photoaging methyl orange degradation:

[0221] Dissolve methyl orange in THF at a concentration of 10 mg / L to create a mother liquor. Dissolve the light extraction material in THF at a concentration of 1 mg / L to create a light extraction material solution. Place 9 ml of the mother liquor in a test tube, then add 1 ml of the light extraction material solution. Vortex to mix thoroughly, and seal the tube to obtain a mixed solution.

[0222] Methyl orange was dissolved in THF to obtain a methyl orange solution having a concentration of 9 mg / L. The absorbance of the methyl orange solution at a wavelength of 460 nm was measured and recorded as the initial absorbance.

[0223] The mixed solution was placed in a QUV-spray UV aging box, using a 340nm lamp with a brightness of 0.8W / m 2 ; The temperature is room temperature; after 18 hours of ultraviolet irradiation, the sample is taken out and the absorbance of the test solution at a wavelength of 460 nm is recorded as the absorbance after light aging.

[0224] Absorption spectrum test:

[0225] The light extraction materials from the examples and comparative examples were vacuum-evaporated onto a glass substrate at a deposition rate of 0.1 nm / s to form a 70 nm thick light extraction layer. A glass substrate was then placed over the light extraction layer to produce a test assembly with a structure of glass substrate / light extraction layer / glass substrate. The test assemblies were divided into two groups: one group was irradiated with UV light for 0 h, and the other group was irradiated with UV light for 144 h. The test assemblies were tested using a UV-visible absorption spectrometer.

[0226] The performance parameters of each embodiment and comparative example are shown in Table 1-Table 3:

[0227] Table 1 Performance parameters of organic electroluminescent devices

[0228]

[0229]

[0230] Note: “\” in Table 1 indicates no corresponding parameter.

[0231] It can be seen from Examples 1-30 and Comparative Examples 1-18 that when the light extraction layer has the same thickness, the red organic electroluminescent device and the green organic electroluminescent device containing the compound of the present application have a higher current efficiency, and the blue organic electroluminescent device containing the compound of the present application has a higher blue light index, indicating that the organic electroluminescent device containing the compound provided by the present application has better luminescence performance.

[0232] Regarding the red organic electroluminescent device and the green organic electroluminescent device, it can be seen from Examples 1 to 10 and Comparative Examples 1 to 10 that, at the same light extraction layer thickness, the current efficiency of the organic electroluminescent devices obtained in the examples is greater than that of the comparative examples. As the thickness of the light extraction layer changes, the CIEx and CIEy of the red and green organic electroluminescent devices change slightly. At the same time, among the red organic electroluminescent devices, for the red organic electroluminescent device containing compound 1-1, the thickness of the light extraction layer increases from 50nm to 90nm, and the current efficiency increases from 42cd / A to 54cd / A, an increase of 12cd / A; while for the red organic electroluminescent device containing compound A2 of the present application, the current efficiency increases from 44cd / A to 59cd / A, an increase of 15cd / A. In the green organic electroluminescent devices, as the light extraction layer thickness increased from 50 nm to 90 nm, the current efficiency of the green organic electroluminescent device containing compound 1-1 increased by 9 cd / A, from 122 cd / A to 131 cd / A. For the green organic electroluminescent device containing compound A2 of the present application, the current efficiency increased by 17 cd / A, from 129 cd / A to 146 cd / A. This indicates that, with the same change in light extraction layer thickness, the current efficiency of the red and green organic electroluminescent devices obtained in the examples increased more significantly than that of the comparative examples, indicating that the red and green organic electroluminescent devices containing the compounds of the present application exhibited better luminescence performance.

[0233] Regarding blue-light organic electroluminescent devices, it can be seen from Examples 11 to 15 and Comparative Examples 11 to 15 that, at the same light extraction layer thickness, the blue light index of the organic electroluminescent devices obtained in the examples is greater than that of the comparative examples, and the CIEy values are all lower than those of the comparative examples, indicating that the blue light color saturation of the blue-light organic electroluminescent devices containing the compounds of the present application is higher. For the blue-light organic electroluminescent device containing compound 1-1, when the light extraction layer thickness increases from 50nm to 90nm, the blue light index decreases from 89 to 77, a decrease of 12, and the CIEy increases from 0.059 to 0.083, an increase of 0.024. For the blue-light organic electroluminescent device containing compound A2 of the present application, when the light extraction layer thickness increases from 50nm to 90nm, the blue light index decreases from 100 to 92, a decrease of 8, and the CIEy increases from 0.052 to 0.058, an increase of 0.006. It can be seen that when the thickness of the light extraction layer changes by the same amount, the decrease in the blue light index and the red shift of the blue light of the blue light organic electroluminescent device obtained in the embodiment are smaller than those in the comparative example, indicating that the blue light organic electroluminescent device containing the compound of the present application has better luminescence performance and higher luminescent color saturation.

[0234] Table 2 Refractive index and light aging performance parameters of light extraction materials

[0235]

[0236] It can be seen from Table 2 that different light extraction materials have certain differences in the refractive index at the same wavelength, and when the compound provided in the present application is used for the light extraction material, its refractive index of red light, blue light and green light is higher than that of the comparative example, indicating that the compound provided in the present application has a higher refractive index when used as a light extraction material.

[0237] After 18 hours of light aging experiments, the absorbance of the methyl orange solution of compounds 1-1 and 1-2 decreased from 0.68 to 0.24 and 0.31, respectively, a decrease of 0.44 and 0.36, respectively, indicating that the methyl orange solution underwent significant decomposition under ultraviolet light irradiation. However, after 18 hours of light aging experiments, the absorbance of the compounds provided in this application was in the range of 0.48-0.51 after light aging, which was significantly higher than the absorbance of compounds 1-1 and 1-2 after light aging. This experiment shows that the addition of the light extraction material provided in this application significantly absorbs ultraviolet rays, effectively protecting the methyl orange dye in the solution, and the compound itself also has good light stability.

[0238] Table 3 Performance parameters of blue organic electroluminescent devices under UV aging test

[0239]

[0240]

[0241] As can be seen from Table 3, the voltage of the blue organic electroluminescent devices in Comparative Examples 13 and 18 increased by 3%-4% and the BI decreased by 7%-8% after the ultraviolet aging test, indicating that the blue organic electroluminescent devices underwent a significant aging process. The main reason for the decrease in BI value may be the aging of the light extraction material, which leads to a decrease in transmittance. The increase in voltage of the blue organic electroluminescent device indicates that the organic layer inside the blue organic electroluminescent device is also damaged by ultraviolet light. However, the BI of the blue organic electroluminescent devices in Examples 13, 18, 21, 24, 27, and 30 decreased by 1%-3%, which is a smaller decrease. The voltage of the blue organic electroluminescent device remains unchanged or increases slightly by 1%-2%, indicating that the light extraction material provided in the present application has strong light stability and can also protect the organic layer inside the blue organic electroluminescent device, thereby improving the ultraviolet weathering resistance of the blue organic electroluminescent device.

[0242] Figure 2 The absorption spectra of Example 13 and Comparative Example 13 are shown. Figure 2 (a) shows the absorption spectra of the light extraction material of Example 13 when irradiated with ultraviolet light for 0 h and 144 h. Figure 2 (b) shows the absorption spectra of the light extraction material of Comparative Example 13 after irradiation with ultraviolet light for 0 h and 144 h. Figure 2 As shown in Figures (a) and (b), after 144 hours of UV irradiation, the absorption intensity of Example 13, using the light extraction material of the present application, decreased significantly less than that of Comparative Example 13, which used a light extraction material from the prior art. The absorbance at the absorption peak of 377nm decreased by 6.3% in Comparative Example 13, while the absorbance at the absorption peak of 379nm in Example 13 decreased by only 1.7%, indicating that the light extraction material of the present application is less affected by UV light and has a stronger tolerance to UV light.

[0243] The above description is only a preferred embodiment of the present application and is not intended to limit the scope of protection of the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application are included in the scope of protection of the present application.

Claims

1. A compound having a structure as shown in formula (I): in, R is selected from hydrogen, deuterium or methyl; X1 and X2 are each independently selected from any one of the following groups: L1-L3 are each independently selected from a single bond or any one of the following subunits:

2. The compound according to claim 1, wherein The compound is selected from any one of the following compounds A1-A10, A13-A17, A20-A23, A27-A29, A32-A35, A40-A49, A55:

3. A light extraction material comprising at least one of the compounds according to any one of claims 1 to 2.

4. The light extraction material according to claim 3, wherein The refractive index of the light extraction material is ≥1.

90.

5. The light extraction material according to claim 3, wherein The light extraction material has a red light refractive index of ≥1.90, a green light refractive index of ≥1.99, and a blue light refractive index of ≥2.

19.

6. An organic electroluminescent device comprising at least one of the light extraction materials according to any one of claims 3 to 5. A display device comprising the organic electroluminescent device according to claim 6 .

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